The present invention is directed to the use of aerogels, particularly to carbon aerogel electrodes, and more particularly to a composite carbon foam electrode and method of fabrication wherein solid carbon, carbon aerogel, or metal particles are added during the process.
Aerogels, carbon aerogels, and carbon foams have been produced by various methods for a variety of applications. These prior processes are exemplified by U.S. Pat. No. 4,806,290 issued Feb. 21, 1989 to R. W. Hopper et al; U.S. Pat. No. 4,873,218 issued Oct. 10, 1989 to R. W. Pekala; U.S. Pat. No. 4,997,804 issued Mar. 5, 1991 to R. W. Pekala; U.S. Pat. No. 5,086,085 issued Feb. 4, 1992 to R. W. Pekala; and U.S. Pat. No. 5,252,620 issued Oct. 12, 1993 to J. R. Elliott, Jr. et al. Recently, efforts have been directed to the development of carbon foams for use as electrodes and include all forms of carbon foams, monolithic, granular or microspheres. Such electrodes find use in energy storage devices, i.e. capacitors and batteries, as well as for fuel cells and electrocapacitive deionization devices, etc. These efforts are exemplified by U.S. Pat. No. 5,260,855 issued Nov. 9, 1993 to J. L. Kaschmitter et al., and U.S. application Ser. No. 08/036,740 filed Mar. 25, 1993, entitled "Carbon Foams For Energy Storage Devices", now U.S. Pat. No. 5,529,971 issued Jun. 25, 1996; Ser. No. 08/041,503 filed Apr. 1, 1993, entitled "Method Of Low Pressure And/Or Evaporated Drying Of Aerogel", now U.S. Pat. No. 5,420,168 issued May 20, 1995; and Ser. No. 08/089,119 filed Jul. 8, 1993, entitled "Organic Aerogel Microspheres And Fabrication Method Therefor", now U.S. Pat. No. 5,508,341 issued Apr. 16, 1996.
It has been discovered by the present invention that manufacturability and performance of these prior carbon foams for electrode applications can be enhanced by using these prior materials as particles with a carbon foam binder to form a composite electrode. Manufacturability would be enhanced by allowing precursor materials to be spread in very thin films or as thin films on roll to roll substrates. Also, performance could be further enhanced by mixing other high performance carbons, in particulate form with the precursor, prior to firing. Thus, this invention provides a composite carbon foam electrode and method for fabricating same.